Originally Posted by Peter M

You both check-in with UA at IAD, and with BMI in Glasgow, ask for "New Economy seats" for extra leg room. Your hand luggage will be checked through to Glasgow, that's where you'll clear customs. The MAN-GLA flight is a small RJ so space is very tight. They can do airside pick up for bulky handluggage.

It's very annoying to arrive at MAN early in the morning and have to wait for immigration to open the doors, X-ray your hand luggage, and allow you into the main airport terminal to catch your connection. Soon, you'll find out what I'm writing about!